In spite of the enormous advance attained by the modern pneumatic tire in absorbing and suppressing road shocks,a very substantial amount of shock and vibration still is passed on by the tire to the standard metallic rim. The rim being fixed to or integral with the wheel and/or the metallic hub fixed therein, passes on shocks through the springs to the body. Lower tire pressures and softer springing have reduced the amount of shock and vibration thus transmitted, but these resorts bring other well known drawbacks in their turn, e.g., reduced handling precision.
An example of prior art resilient wheels includes U.S. Pat. No. 2,891,593 to Deuring et al. It disclosed a wheel having two rubber shock absorbing rings vulcanized to a divided rim, one ring to a supporting disc attached to the main wheel disc or hub, the other to an annular flange secured to the disc and diverging from the supporter ring. U.S. Pat. No. 2,903,036 to Walfram also discloses two rubber rings secured to annular rings bolted to bosses on the wheel hub and secured to the outer tire rim.
In both of these patents, the rubber shock absorbing rings are exposed directly to ambient air pressure on both their sides relying completely on their own resilience to absorb shocks.
In my prior U.S. Pat. No. 3,090,415, I disclosed a pneumatic tired vehicle wheel in which the rim was separated from the hub by a single band of rubber or other elastomeric material which isolated the hub from shock imparted to the tire or rim. In accordance with that invention, the rim is separated from all metallic contact with the wheel and/or hub of the vehicle by suspending the wheel within the rim in a continuous band of elastomeric material bonded to the rim along its lateral margins. The elastomeric material is also bonded to extensions or "spokes" on the wheel in alignment with apertures provided in the otherwise continuous felloe of the rim. The elastomeric material is subjected at such apertures to the air pressure within the tires, directly in the case of tubeless tires and through the intervening tube when such is used, so that the elastomeric material is stressed when the tire was inflated, imparting stability to the assembly.
To overcome this difficulty, I developed an improved resilient wheel forming the subject matter of U.S. Pat. No. 4,549,590, in which there is a central hub with a shock absorbing member between the rim and the central hub. It comprises an annular, pneumatically sealed, hollow, substantially toroidal member, at least a portion of which is flexible. Both the rim and the hub are attached to the toroidal member, one of which is attached to the flexible portion whereby shocks imparted to the rim are absorbed by the flexible portion and the air within the toroidal member.
Due to the possibility that the resilient wheel disclosed in my U.S. Pat. No. 4,549,590 might be susceptible to the shock absorbing member becoming disengaged from either the annular, substantially toroidal member surrounding the central hub or a cup like annular channel to which it is sealed, I developed a reinforced resilient wheel as disclosed in my U.S. Pat. No. 4,765,382. This wheel included a rim, a hub, and a shock absorbing air space formed between the channel and the elastomeric member. The wheel also included flange means clamping the elastomeric member to the rim, and reinforcing means for securing the elasomeric member to the rim, thus preventing disengagement of the shock absorbing member.
The evolution of the above-mentioned inventions led to the idea of a wheel with a cushioning effect derived from multiple air chambers within the wheel. The present invention is directed to a wheel having a continuous, impervious elastomeric member between the rim and the interior of the tire which creates two opposed air chambers acting in concert to absorb shock.